The present invention relates to measurement of the blood pressure of a patient.
The invention relates particularly to a procedure which is based on the method of Riva-Rocci/Korotkoff, and in which the patient himself secures an inflatable pressure cuff in place and switches a switch into a first switch position to automatically close a valve, subsequent opening of the valve after the cuff has been inflated permitting the air in the cuff to slowly escape. Simultaneously a battery-fed current supply circuit is switched on, two indicators of a dual indicator manometer, which are blocked when the current supply circuit is switched off, are released by exciting respective electromagnets, and an electronic barrier is switched on to prevent blocking of the indicators. Thereafter the patient pumps the cuff to a pressure which lies above his systolic blood pressure and switches the switch into a second switch position to open the valve, and an electrical device detects the start or stop, respectively, of the Korotkoff noise and blocks, at the respective start or stop, one of the indicators of the manometer. Blocking is effected by interrupting the circuit for one of the electromagnets. The electrical device also switches off the electrical circuit after both indicators have been blocked.
The present invention is based on a blood pressure measuring method in which the inflatable blood pressure cuff initially exerts, on an artery, a pressure above the patient's systolic pressure value, the cuff pressure is then gradually reduced and electrical signals are derived from the resulting Korotkoff sounds, a first indicator of a dual-indicator manometer which is influenced by the cuff pressure is blocked at the commencement of such signals, which occurs at the systolic pressure value, and the second indicator of the manometer is blocked upon termination of such signals, this occurring at the diastolic pressure value.
A sphygmomanometer which has a separate automatic indication for the systolic and diastolic pressure values is disclosed in German Offenlegungsschrift [Laid-open Application] No. DT-OS 22 09 633, which gives no precise information about the circuitry of the sphygmomanometer. Moreover, this sphygmomanometer has a relatively high current consumption and that publication provides no indication as to how this current consumption could be reduced.
Furthermore, U.S. Pat. No. 3,056,401 discloses a self-recording sphygmomanometer which has substantially the same drawbacks, although in this device no current is consumed when the indicators of the dual indicator manometer are blocked.